1. Technical Field
The present invention relates to a flow meter using digital signals which measures a flow rate of a fluid by detecting a position of a float in a tapered tube by an image sensor.
2. Background Art
The present applicant proposed an accurate, small-sized and inexpensive variable-area flow meter with sensor in Japanese Patent Laid-Open No. 2001-221666.
In this conventional variable-area flow meter with sensor, a float vertically moved by a flow rate is provided in a tapered tube having light transmittance, and a fluid to be measured flows in from an inflow port at a lower part toward an inflow port at an upper part, and a plurality of pairs of image sensor units comprised by an optical lens and an image sensor are arranged along the single side of the tapered tube in the vertical direction.